Hanbyul Seo

LG Electronics

Overview of 5G C-V2X standard

Vehicle-to-everything (V2X)

V2X is a set of services enabled by vehicular communications.

– V2V: Vehicle-to-Vehicle

– V2P: Vehicle-to-Pedestrian

Handheld terminal carried by a pedestrian, cyclist, driver or passenger

– V2I: Vehicle-to-Infrastructure application

RSU (Roadside Unit) is the transportation infrastructure entity.

– V2N: Vehicle-to-Network

Communication with application servers

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Why V2X is necessary?

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One of the main enabler of highly automated driving

– International transport forum, “Automated and Autonomous Driving”, 2015

“Vehicle-to-X connectivity (V2X): Connectivity is an important element of the automated vehicles especially secure V2X communication requiring low latency. V2X technologies encompass the use of wireless technologies to achieve real-time two-way communication among vehicles (V2V) and between vehicles and infrastructure (V2I). The convergence of sensor-based solutions (current advanced driver assistance - ADAS) and V2X connectivity will promote automated driving.”

V2X allows information collection othersensors cannot do.

– Can know the situation even whenthe line-of-sight is blocked.

– Less impacted by the circumstance,e.g., weather, light, …

– Even allows collecting invisible information such as the intended maneuver in the future

Radar

Camera

Lidar

Ulatrasonic

V2X

3D HD Map

Precise positioning

Basic V2X services – Day 1

4

Electric emergency brake light

Control loss warningEmergency vehicle alert

Road hazard warning

Curve speed warning

Forward collision warning

Vulnerable user safety

(may be a part of

advanced services)

Signal phase and timing

Traffic flow control

Advanced V2X services – Day 2

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From http://www.sarte-project.eu

(1)

(2)

From 3GPP TR 22.886

Collective perception

Maneuver coordination Platooning & group start

Tele-operated driving

V2X service requirements

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Main performance metrics

– Latency: Upper bound of message transmission latency is of more importance.

– Reliability: Typically in terms of the probability of failure in delivering the messages to the target receiver(s).

– Data rate: Peak data rate as well as the average data rate

• Predictable message generation• Small message size• Relaxed latency & reliability requirements

• Unpredictable message generation• Large message size• Stringent latency & reliability requirements

Day-1 Day-2

C-V2X standards

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Cellular V2X (C-V2X) is V2X based on cellular technology such as LTE and NR.

– Uu and PC5 interfaces for C-V2X

Sidelink (used for PC5 interface) Uplink & downlink (used for Uu interface)

Pros - Shorter latency- Local communication with spatial resource reuse- Operation even outside network coverage

- Larger coverage- Reuse existing infrastructure (V2I or V2N)- More efficient centralized control

Cons - Limited coverage- Limitation in controlling multiple devices

- Longer latency in V2V and V2P- No support for out-coverage operations

Sidelink (D2D)

Control may be provided by the

network.

C-V2X standards

Multiple phases for evolution of C-V2X technologies.

– Started from LTE-based V2X standards

– Initial release of 5G NR based V2X standards are completed.

Non-compatible PHY format is used, but device-level compatibility and coexistence can be supported.

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3GPP V2X phase 2 based on LTE

3GPP V2X phase 1 based on LTE

Backward compatible

Non-backward compatible

3GPP V2X evolution path

3GPP V2X phase 3 based on NR

5GLTE Evolution

New RadioTight Integration

March 2017 June 2018

Rel-15Rel-14

June 2020

Rel-16

March 2022 (TBD)

Rel-17

3GPP V2X phase 4 based on NR

Backward compatible

C-V2X standards

Vehicle communications in 3GPP releases

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LTE Uu(V2N service)

LTE Uu(basic safety)

LTE PC5(basic safety)

Release 8, 9, …, 13

Release 14

5G

LTE PC5(improvement for

basic safety)NR Uu

(high bandwidth, low latency)

LTE Uu(basic safety)

LTE PC5(basic safety)

NR Uu (enhanced URLLC)

LTE Uu(basic safety)

NR PC5(advanced V2X

support)

Release 15

Release 16

Highlights of Rel-16 NR sidelink

Flexible radio design

– Can cover low-mid frequency bands as well as mmWave spectrum

Operation in a wider band is supported (e.g., 10, 20, 30, 40 MHz in 5.9 GHz)

– Can adapt the physical layer structure

Subcarrier spacing, overhead of reference signals, …

Higher spectral efficiency

– MIMO multi-layer transmissions

– Channel status information feedback for link adaptation

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Control

Time

Frequency

Data

Reference signal

Control

Data

Reference signal

Control

Data

Reference signal

Highlights of Rel-16 NR sidelink

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Hybrid automatic repeat request (HARQ) feedback

– A packet can be retransmitted until it is received by all the intended receivers.

Efficient handling of unpredicted packet generations

– Re-evaluation of the resource reservation and pre-emption for high priority packets

Time

Frequency

Low priority from device 1

High priority from device 2

Resource reservation

Cancel the reserved resource and select an

alternative

Highlights of Rel-16 NR sidelink

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Efficient coexistence with LTE sidelink

– When a device is equipped with both LTE and NR sidelinks

– Radio selection for each generated message

– NR sidelink can be synchronized with LTE sidelink.

NR sidelink can avoid interfering with an important operation in LTE sidelink, and vice versa.

APP Layer

V2X Layer

LTE

sidelink

Message

NR

sidelink

Basic safety message

Advanced use cases message

Thank you!